Expanding mandrel



Dec. 24, 1940. Q SPAHN 2,226,078

EXPANDING MANDREL Filed Spt. 29, 1939 Patented Dec. 24, 1940 EXPANDHTG REL C. Spahn, Kewanee, Ill.

Application September 29, i939, Serial No. 297,173

3 Claims.

This invention relates to mandrels and more particularly to an expanding mandrel especially designed for use by plumbers and others when threading or cutting thin tubes or pipes.

The object of the invention is to provide an expansible mandrel of simple and durable construction adapted to fit within a tube or pipe so as to prevent crushing or denting of the walls thereof when the pipe is clamped in a chuck or vice preparatory to threading the same.

A further object of the invention is to provide a mandrel comprising a plurality of springpressed expansible sections and an operating member extending longitudinally through said sections and provided with coacting tapered heads for forcing said sections laterally against the tension ci the spring into engagement with the inner walls of a pipe.

A still further object of the invention is generally to improve this class of devices so as to increase their utility, durability and efiiciency as well as to reduce the cost of manufacture.

In the accompanying drawing forming a part of this specification and in which similar numerals of reference indicate corresponding parts in all the gures of the drawing:

Figure l is a side elevation of an expanding mandrel embodying the present invention showing the same in position within a tube or pipe,

Figure 2 is a longitudinal sectional view taken on the line 2-2 of Figure 1,

Figure 3 is a transverse sectional view taken on the line .i3- 53 of Figure l with the spring omitted for the sake of clearness,

Figure fl is an end elevation with the adjacent expanding head removed and showing the construction of the receiving socket for said head,

Figure 5 is a View looking at the tapered end of the forward expanding head,

Figure 6 is an end view illustrating a modified form of the invention, the outer expanding head being removed, and

Figure 'l is a transverse sectional view of the structure shown in Figure 6.

The improved expanding mandrel forming the subject-matter of the present invention comprises a supporting rod 5 cylindrical in cross section and. having one end thereof provided with a knurled nger-piece 6 and its other end reduced at 'l to form an extension 8 provided with threads, indicated at t.

Loosely mounted on the extension 8 are a piurality of expansible sections I0, preferably three in number as shown, and having their inner faces cut-away at li to accommodate the extension S3 (Cl. lll-107) and their outer faces formed with circumferential grooves I2 for the reception of coiled springs it. 'Ihe adjacent ends of the coiled springs I3 are provided with interengaging fastening loops It to prevent displacement of the springs and also to 5 permit the springs to be readily removed or replaced when desired. The springs i3 serve to normally and yieldably hold the inner faces i i of the expansible segments it in engagement with the extension d so as to permit the mandrel to be ragily inserted within a tube or pipe, indicated a E5.

The opposite ends or the sectional expanding members are provided with inwardly extending tapered sockets it and it having hexagonal walls` 15 it which engage correspondingly shaped walls i@ on suitable expanding heads, indicated at 2li and 2i. The expanding head 2d is provided with a threaded base for engagement with the threads Si on the extension il while the expanding head El is slidably mounted on the extension d, as shown. The head 2i is provided with a longitudinally disposed sleeve 22 which rits loosely around the supporting rod 5 with its outer end normally bearing against the nger-piece e so that, when said iinger-piece is rotated, the heads 2li and 2l by engagexnent with the angular walls it ofthe sockets it and ii will force the expansible sections iii laterally into clamping engagement with the inner wall of the pipe i5 and thus prevent crushing or bending of the pipe when the latter is clamped in a chuck or vise preparatory to threading said pipe. It will here be noted that the outer ends oi the expansible sections i@ are provided with substantially V-shaped guide notches 2S which receive the angular portions or ribs 2li oi? the adjacent expanding heads, said angular portions or ribs 24 being disposed at the junction of the angular walls of the expanding heads, as best shown in Figure 5 of the drawing.

Under normal conditions, the coiled springs i3 hold the expansible sections against the extension 8 of the supporting rod and in which position the outer surfaces of the expansible sections will be ush or smooth so as to permit the mandrel to be readily inserted in the adjacent end of the pipe i5. After the mandrel has been positioned within the pipe, the nger-piece 6 is rotated and by engagement with the adjacent end of the sleeve 22 forces the head 2i longitudinally of the ex- 50 tension 8 while at the same time the head 2li by engagement with the threads will be fed inwardly, thus expanding the segmental sections lil laterally against the tension of the spring i3 and into engagement with the inner wall of the pipe 55 or'tbe -'5,"`thereby permitting the pipe to be clamped between the jaws of a vice or chuck without danger of crushing the pipe. After the pipe has been threaded, cut or otherwise operated upon, the linger-.piece 6 is rotated in the reverse direction which releases the heads 20 and 2i from engagement with the tapered walls of the sockets I8 and Il, whereupon the springs I3 will contract said sections so as to permit the mandrel to be readily removed' from the pipe or tube.

In Figures 6 and 7 of the drawing, there is illustrated a modified form of the invention, in which the expansible portion of the mandrel is formed in six sections, indicated at 25, and the walls of the sockets for the reception of the expanding heads are provided with twelve angular faces, in-

dicated at 26, instead of six, the construction and operation of the mandrel being otherwise similar to that shown in Figure 1 of the drawing.

The mandrel is exceedingly simple in construction and easy to operateand will effectually retain the walls of relatively thin tubes and pipe sections in their original shape when threading said pipe sections without danger of crushing or denting the same.

It will, of course, be understood that the mandrels may be made in different sizes and shapes and provided with any desired number of expansible sections without departing from the spirit of the invention.

Having thus described the invention, what is claimed as new is:

1. A tool of the class described comprising a rod having one end thereof reduced to form a longitudinal extension provided with a threaded portion and a smooth portion, a sectional expanding member mounted on the rod and provided with oppositely disposed tapered sockets having angular walls, springs surrounding the sections of the expanding member, tapered expanding heads having angular Walls adapted to engage the angular walls of the adjacent sockets, one of said expanding heads having threaded engagement with the threads on the extension and the other head being loosely mounted on the smooth portion of said extension, a sleeve carried by the last-mentioned head and loosely fitting ci? i ,vw over the supporting rod, and a finger-piece on one end o1' said supporting rod and bearing against the sleeve.

2. A tool of the class described comprising a supporting md having one end thereof reduced to form a longitudinal extension, a portion of which is threaded and another portion thereof smooth, a'sectional expanding member mounted on the rod and provided withioppositely disposed tapered sockets having angular walls, there being substantially V-shaped notches foi-med in said sections at the Junction of the angular walls thereof, tapered expanding heads! having correspondingly angular walls fitting within the adjacent sockets, one of said expanding heads engaging the threads on the extension and the other loosely mounted on the smooth portion thereof, a sleeve forming a continuation of the last-mentioned head and loosely mounted on the supporting rod, there being ribs disposed at the junction of the angular walls of the expanding heads and adapted to fit within the V-shaped notches, and a nger-piece mounted on one end of the supporting rod and bearing against the adjacent end of the sleeve.

3. A tool of the class described comprising a supporting rod having one end thereof reduced to form a longitudinal extension, a portion of which is threaded and another portion thereof smooth, a sectional expansible member mounted on the rod and provided with oppositely disposed tapered sockets, there being circumferential grooves formed in said expanding member, springs fitted within said grooves for normally holding the section of the expanding member yieldably in engagement with the rod extension, tapered heads fitting within the adjacent sockets, one of said heads engaging the threads on the extension and the other being loosely mounted on the smooth portion of said extension, a sleeve extending longitudinally from the last-mentioned expanding head and loosely fitting over the supporting rod, and a finger-piece carried by one end of the supporting rod for actuating the heads to expand the sections of said member.

HILBERT C. SPAHN. 

